db.collection.findOneAndUpdate()

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Definition定义

db.collection.findOneAndUpdate(filter, update, options)

mongo Shell Method

This page documents the mongo shell method, and does not refer to the MongoDB Node.js driver (or any other driver) method. 本页记录了mongo shell方法，未提及MongoDB Node.js驱动程序（或任何其他驱动程序）方法。For corresponding MongoDB driver API, refer to your specific MongoDB driver documentation instead.有关相应的MongoDB驱动程序API，请参阅特定的MongoDB驱动程序文档。

New in version 3.2.版本3.2中的新功能。

Updates a single document based on the filter and sort criteria.根据filter和sort条件更新单个文档。

The findOneAndUpdate() method has the following form:findOneAndUpdate()方法的形式如下：

db.collection.findOneAndUpdate(
   <filter>,
   <update document or aggregation pipeline>, // Changed in MongoDB 4.2
   {
     projection: <document>,
     sort: <document>,
     maxTimeMS: <number>,
     upsert: <boolean>,
     returnNewDocument: <boolean>,
     collation: <document>,
     arrayFilters: [ <filterdocument1>, ... ]
   }
)

The findOneAndUpdate() method takes the following parameters:findOneAndUpdate()方法采用以下参数：

Parameter参数Type类型Description描述
filter document

The selection criteria for the update. 更新的选择标准。The same query selectors as in the find() method are available.与find()方法中相同的查询选择器可用。

Specify an empty document { } to update the first document returned in the collection.指定一个空文档{ }，以更新集合中返回的第一个文档。

If unspecified, defaults to an empty document.如果未指定，则默认为空文档。

Starting in MongoDB 4.2 (and 4.0.12+, 3.6.14+, and 3.4.23+), the operation errors if the query argument is not a document.从MongoDB 4.2（以及4.0.12+、3.6.14+和3.4.23+）开始，如果查询参数不是文档，则会出现操作错误。

update document or 或array

The update document or, starting in MongoDB 4.2, an aggregation pipeline.更新文档，或者从MongoDB 4.2开始的聚合管道。

projection document

Optional.可选。A subset of fields to return.要返回的字段的子集。

To return all fields in the returned document, omit this parameter.要返回返回的文档中的所有字段，请忽略此参数。

Starting in MongoDB 4.2 (and 4.0.12+, 3.6.14+, and 3.4.23+), the operation errors if the projection argument is not a document.从MongoDB 4.2（以及4.0.12+、3.6.14+和3.4.23+）开始，如果投影参数不是文档，则会出现操作错误。

sort document

Optional.可选。Specifies a sorting order for the documents matched by the filter.为由filter匹配的文档指定排序顺序。

Starting in MongoDB 4.2 (and 4.0.12+, 3.6.14+, and 3.4.23+), the operation errors if the sort argument is not a document.从MongoDB 4.2（以及4.0.12+、3.6.14+和3.4.23+）开始，如果排序参数不是文档，则会出现操作错误。

See cursor.sort().请参见cursor.sort()。

maxTimeMS number Optional.可选。Specifies a time limit in milliseconds within which the operation must complete within. 以毫秒为单位指定操作必须在内完成的时间限制。Throws an error if the limit is exceeded.如果超出限制，则引发错误。
upsert boolean

Optional.可选。When true, findOneAndUpdate() either:如果为true，则findOneAndUpdate()可以：

  • Creates a new document if no documents match the filter. 如果没有与filter匹配的文档，则创建新文档。For more details see upsert behavior. 有关更多详细信息，请参阅upsert行为。Returns null after inserting the new document, unless returnNewDocument is true.插入新文档后返回null，除非returnNewDocument为true。
  • Updates a single document that matches the filter.更新与filter匹配的单个文档。

To avoid multiple upserts, ensure that the filter fields are uniquely indexed.要避免多个Upsert，请确保筛filter字段的索引是唯一的。

Defaults to false.默认为false。

returnNewDocument boolean

Optional.可选。When true, returns the updated document instead of the original document.如果为true，则返回更新的文档，而不是原始文档。

Defaults to false.默认为false。

collation document

Optional.可选。

Specifies the collation to use for the operation.指定要用于该操作的排序规则。

Collation排序规则 allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音符号的规则。

The collation option has the following syntax:collation选项语法如下所示：

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. 指定排序规则时，locale字段是必需的；所有其他排序规则字段都是可选的。For descriptions of the fields, see Collation Document.有关这些字段的描述，请参阅排序规则文档。

If the collation is unspecified but the collection has a default collation (see db.createCollection()), the operation uses the collation specified for the collection.如果未指定排序规则，但集合具有默认排序规则（请参见db.createCollection()），则操作将使用为集合指定的排序规则。

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.如果没有为集合或操作指定排序规则，MongoDB将使用以前版本中用于字符串比较的简单二进制比较。

You cannot specify multiple collations for an operation. 不能为一个操作指定多个排序规则。For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.例如，不能为每个字段指定不同的排序规则，或者如果使用排序执行查找，则不能对查找使用一种排序规则，对排序使用另一种排序规则。

New in version 3.4.版本3.4中的新功能。

arrayFilters array

Optional.可选。An array of filter documents that determine which array elements to modify for an update operation on an array field.筛选文档的数组，用于确定要为数组字段上的更新操作修改哪些数组元素。

In the update document, use the $[<identifier>] filtered positional operator to define an identifier, which you then reference in the array filter documents. 在更新文档中，使用$[<identifier>]筛选的位置运算符定义一个标识符，然后在数组筛选文档中引用该标识符。You cannot have an array filter document for an identifier if the identifier is not included in the update document.如果标识符未包含在更新文档中，则不能使用标识符的数组筛选器文档。

Note

The <identifier> must begin with a lowercase letter and contain only alphanumeric characters.<identifier>必须以小写字母开头，并且只包含字母数字字符。

You can include the same identifier multiple times in the update document; however, for each distinct identifier ($[identifier]) in the update document, you must specify exactly one corresponding array filter document. 您可以在更新文档中多次包含同一标识符；但是，对于更新文档中的每个不同标识符（$[identifier]），必须指定一个对应的数组筛选器文档。That is, you cannot specify multiple array filter documents for the same identifier. 也就是说，不能为同一标识符指定多个数组筛选器文档。For example, if the update statement includes the identifier x (possibly multiple times), you cannot specify the following for arrayFilters that includes 2 separate filter documents for x:例如，如果update语句包含标识符x（可能多次），则不能为包含x的两个单独筛选文档的arrayFilters指定以下内容：

// INVALID

[
  { "x.a": { $gt: 85 } },
  { "x.b": { $gt: 80 } }
]

However, you can specify compound conditions on the same identifier in a single filter document, such as in the following examples:但是，您可以在单个筛选文档中对同一标识符指定复合条件，如以下示例中所示：

// Example 1
[
  { $or: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] }
]
// Example 2
[
  { $and: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] }
]
// Example 3
[
  { "x.a": { $gt: 85 }, "x.b": { $gt: 80 } }
]

For examples, see Array Update Operations with arrayFilters.有关示例，请参阅使用arrayFilters的数组更新操作。

Note

arrayFilters is not available for updates that use an aggregation pipeline.不适用于使用聚合管道的更新。

New in version 3.6.版本3.6中的新功能。

Returns:返回：Returns either the original document or, if returnNewDocument: true, the updated document.返回原始文档，如果returnNewDocument:true，则返回更新的文档。

Behavior行为

Document Match文档匹配

db.collection.findOneAndUpdate() updates the first matching document in the collection that matches the filter. 更新集合中与filter匹配的第一个匹配文档。The sort parameter can be used to influence which document is updated.sort参数可用于影响更新的文档。

Projection投影

Language Consistency语言一致性

Starting in MongoDB 4.4, as part of making find and findAndModify projection consistent with aggregation’s $project stage,从MongoDB 4.4开始，作为使用find和findAndModify投影与聚合的$project阶段保持一致的一部分，

The projection parameter takes a document in the following form:projection参数采用以下形式的文档：

{ field1 : <value>, field2 : <value> ... }
Projection投影Description描述
<field>: <1 or true> Specifies the inclusion of a field.指定字段的包含。
<field>: <0 or false> Specifies the exclusion of a field.指定字段的排除。
"<field>.$": <1 or true> With the use of the $ array projection operator, you can specify the projection to return the first element that match the query condition on the array field; e.g. "arrayField.$" : 1. 使用$数组投影运算符，可以指定投影以返回与数组字段上的查询条件匹配的第一个元素；例如，"arrayField.$" : 1。(Not available for views.)（不适用于视图。）
<field>: <array projection> Using the array projection operators $elemMatch, $slice, specifies the array element(s) to include, thereby excluding those elements that do not meet the expressions. 使用数组投影运算符$elemMatch，$slice，指定要包含的数组元素，从而排除那些不符合表达式的元素。(Not available for views.)（不适用于视图。）
<field>: <aggregation expression>

Specifies the value of the projected field.指定投影字段的值。

Starting in MongoDB 4.4, with the use of aggregation expressions and syntax, including the use of literals and aggregation variables, you can project new fields or project existing fields with new values. 从MongoDB 4.4开始，通过使用聚合表达式和语法，包括使用文字和聚合变量，可以投影新字段或使用新值投影现有字段。For example,例如

  • If you specify a non-numeric, non-boolean literal (such as a literal string or an array or an operator expression) for the projection value, the field is projected with the new value; e.g.:如果为投影值指定非数字、非布尔文字（例如文字字符串、数组或运算符表达式），则会使用新值投影字段；如：
    • { field: [ 1, 2, 3, "$someExistingField" ] }
    • { field: "New String Value" }
    • { field: { status: "Active", total: { $sum: "$existingArray" } } }
  • To project a literal value for a field, use the $literal aggregation expression; e.g.:要为字段投影文字值，请使用$literal聚合表达式；如：
    • { field: { $literal: 5 } }
    • { field: { $literal: true } }
    • { field: { $literal: { fieldWithValue0: 0, fieldWithValue1: 1 } } }

In versions 4.2 and earlier, any specification value (with the exception of the previously unsupported document value) is treated as either true or false to indicate the inclusion or exclusion of the field.在版本4.2和更早版本中，任何规范值（以前不支持的文档值除外）都被视为true或false，以指示包含或排除该字段。

New in version 4.4.版本4.4中的新功能。

Embedded Field Specification嵌入式字段规范

For fields in an embedded documents, you can specify the field using either:对于嵌入文档中的字段，可以使用以下任一方法指定字段：

  • dot notation; e.g. "field.nestedfield": <value>点记号法；例如，"field.nestedfield": <value>
  • nested form; e.g. { field: { nestedfield: <value> } } (Starting in MongoDB 4.4)嵌套形式；例如{ field: { nestedfield: <value> } }（从MongoDB 4.4开始）

_id Field Projection场投影

The _id field is included in the returned documents by default unless you explicitly specify _id: 0 in the projection to suppress the field.默认情况下，_id字段包含在返回的文档中，除非在投影中明确指定_id:0以抑制该字段。

Inclusion or Exclusion包含还是排除

A projection cannot contain both include and exclude specifications, with the exception of the _id field:projection不能同时包含包含和排除规范，但_id字段除外：

  • In projections that explicitly include fields, the _id field is the only field that you can explicitly exclude.在显式包含字段的投影中，_id字段是唯一可以显式排除的字段。
  • In projections that explicitly excludes fields, the _id field is the only field that you can explicitly include; however, the _id field is included by default.在显式排除字段的投影中，_id字段是唯一可以显式包括的字段；但是，默认情况下会包含_id字段。

For more information on projection, see also:有关投影的更多信息，请参阅：

Sharded Collections分片集合

To use db.collection.findOneAndUpdate() on a sharded collection, the query filter must include an equality condition on the shard key.

Starting in version 4.4, documents in a sharded collection can be missing the shard key fields. To target a document that is missing the shard key, you can use the null equality match in conjunction with another filter condition (such as on the _id field). For example:例如：

{ _id: <value>, <shardkeyfield>: null } // _id of the document missing shard key

Shard Key Modification

Starting in MongoDB 4.2, you can update a document’s shard key value unless the shard key field is the immutable _id field. Before MongoDB 4.2, a document’s shard key field value is immutable.

Warning

Starting in version 4.4, documents in sharded collections can be missing the shard key fields. Take precaution to avoid accidentally removing the shard key when changing a document’s shard key value.从4.4版开始，分片集合中的文档可能会缺少分片键字段。采取预防措施，以避免在更改文档的shard key值时意外删除shard key。

To modify the existing shard key value with db.collection.findOneAndUpdate():要修改现有的db.collection.findOneAndUpdate()值

  • You must run on a mongos. Do not issue the operation directly on the shard.
  • You must run either in a transaction or as a retryable write.
  • You must include an equality filter on the full shard key.必须在完整分片键上包含相等筛选器。

Missing Shard Key缺失分片键

Starting in version 4.4, documents in a sharded collection can be missing the shard key fields. To use db.collection.findOneAndUpdate() to set the document’s missing shard key,

  • You must run on a mongos. Do not issue the operation directly on the shard.
  • You must run either in a transaction or as a retryable write if the new shard key value is not null.
  • You must include an equality filter on the full shard key.必须在完整分片键上包含相等筛选器。

Tip

Since a missing key value is returned as part of a null equality match, to avoid updating a null-valued key, include additional query conditions (such as on the _id field) as appropriate.由于缺少的键值是作为空相等匹配的一部分返回的，为了避免更新空值键值，请酌情包括其他查询条件（例如在_id字段上）。

See also:参阅：

Transactions事务

db.collection.findOneAndUpdate() can be used inside multi-document transactions.可以在多文档事务中使用。

Important

In most cases, multi-document transaction incurs a greater performance cost over single document writes, and the availability of multi-document transactions should not be a replacement for effective schema design. 在大多数情况下，与单文档写入相比，多文档事务会带来更大的性能成本，而多文档事务的可用性不应取代有效的模式设计。For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases. 对于许多场景，非规范化数据模型（嵌入式文档和数组）将继续适合您的数据和用例。That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions.也就是说，对于许多场景，适当地建模数据将最大限度地减少对多文档事务的需求。

For additional transactions usage considerations (such as runtime limit and oplog size limit), see also Production Considerations.有关其他事务使用注意事项（如运行时限制和oplog大小限制），请参阅生产注意事项。

Upsert within Transactions在事务中插入

Starting in MongoDB 4.4 with feature compatibility version (fcv) "4.4", you can create collections and indexes inside a multi-document transaction if the transaction is not a cross-shard write transaction.

As such, for the feature compatibility version (fcv) is "4.4" or greater, db.collection.findOneAndUpdate() with upsert: true can be run against an existing collection or a non-existing collection. If run against a non-existing collection, the operation creates the collection.如果针对不存在的集合运行，该操作将创建该集合。

If the feature compatibility version (fcv) is "4.2" or less, the operation must be against an existing collection.如果功能兼容版本（fcv）为"4.2"或更低，则操作必须针对现有集合。

See also参阅

Create Collections and Indexes In a Transaction在事务中创建集合和索引

Write Concerns and Transactions撰写关注事项和交易记录

Do not explicitly set the write concern for the operation if run in a transaction. 如果在事务中运行，请不要显式设置操作的写入关注点。To use write concern with transactions, see Transactions and Write Concern.要将写关注点用于事务，请参阅事务和写关注点。

Examples示例

Update A Document更新文档

The grades collection contains documents similar to the following:grades集合包含与以下类似的文档：

{ _id: 6305, name : "A. MacDyver", "assignment" : 5, "points" : 24 },
{ _id: 6308, name : "B. Batlock", "assignment" : 3, "points" : 22 },
{ _id: 6312, name : "M. Tagnum", "assignment" : 5, "points" : 30 },
{ _id: 6319, name : "R. Stiles", "assignment" : 2, "points" : 12 },
{ _id: 6322, name : "A. MacDyver", "assignment" : 2, "points" : 14 },
{ _id: 6234, name : "R. Stiles", "assignment" : 1, "points" : 10 }

The following operation finds the first document where name : R. Stiles and increments the score by 5:下面的操作将查找第一个name为R. Stiles的文档，并将score增加5：

db.grades.findOneAndUpdate(
   { "name" : "R. Stiles" },
   { $inc: { "points" : 5 } }
)

The operation returns the original document before the update:操作将在更新之前返回原始文档：

{ _id: 6319, name: "R. Stiles", "assignment" : 2, "points" : 12 }

If returnNewDocument was true, the operation would return the updated document instead.如果returnNewDocument为true，则操作将返回更新后的文档。

Sort And Update A Document对文档进行排序和更新

The grades collection contains documents similar to the following:grades集合包含与以下类似的文档：

{ _id: 6305, name : "A. MacDyver", "assignment" : 5, "points" : 24 },
{ _id: 6308, name : "B. Batlock", "assignment" : 3, "points" : 22 },
{ _id: 6312, name : "M. Tagnum", "assignment" : 5, "points" : 30 },
{ _id: 6319, name : "R. Stiles", "assignment" : 2, "points" : 12 },
{ _id: 6322, name : "A. MacDyver", "assignment" : 2, "points" : 14 },
{ _id: 6234, name : "R. Stiles", "assignment" : 1, "points" : 10 }

The following operation updates a document where name : "A. MacDyver". 以下操作将更新一个名为name : "A. MacDyver"的文档。The operation sorts the matching documents by points ascending to update the matching document with the least points.该操作按points升序对匹配文档进行排序，以使用最少的点更新匹配文档。

db.grades.findOneAndUpdate(
   { "name" : "A. MacDyver" },
   { $inc : { "points" : 5 } },
   { sort : { "points" : 1 } }
)

The operation returns the original document before the update:操作将在更新之前返回原始文档：

{ _id: 6322, name: "A. MacDyver", "assignment" : 2, "points" : 14 }

Project the Returned Document投影返回的文档

The following operation uses projection to only display the _id, points, and assignment fields in the returned document:

db.grades.findOneAndUpdate(
   { "name" : "A. MacDyver" },
   { $inc : { "points" : 5 } },
   { sort : { "points" : 1 }, projection: { "assignment" : 1, "points" : 1 } }
)

The operation returns the original document with only the fields specified in the projection document and the _id field as it was not explicitly suppressed (_id: 0) in the projection document.

{ "_id" : 6322, "assignment" : 2, "points" : 14 }

Update Document with Time Limit有时间限制的文件更新

The following operation sets a 5ms time limit to complete the update:以下操作设置了5毫秒的时间限制以完成更新：

try {
   db.grades.findOneAndUpdate(
      { "name" : "A. MacDyver" },
      { $inc : { "points" : 5 } },
      { sort: { "points" : 1 }, maxTimeMS : 5 };
   );
}
catch(e){
   print(e);
}

If the operation exceeds the time limit, it returns:如果操作超过时间限制，则返回：

Error: findAndModifyFailed failed: { "ok" : 0, "errmsg" : "operation exceeded time limit", "code" : 50 }

Update Document with Upsert用Upsert更新文档

The following operation uses the upsert field to insert the update document if nothing matches the filter:如果没有与filter匹配的内容，以下操作将使用upsert字段插入更新文档：

try {
db.grades.findOneAndUpdate(
   { "name" : "A.B. Abracus" },
   { $set: { "name" : "A.B. Abracus", "assignment" : 5}, $inc : { "points" : 5 } },
   { sort: { "points" : 1 }, upsert:true, returnNewDocument : true }
);
}
catch (e){
   print(e);
}

The operation returns the following:该操作返回以下内容：

{
   "_id" : ObjectId("5789249f1c49e39a8adc479a"),
   "name" : "A.B. Abracus",
   "assignment" : 5,
   "points" : 5
}

If returnNewDocument was false, the operation would return null as there is no original document to return.

Specify Collation指定排序规则

New in version 3.4.版本3.4中的新功能。

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.排序规则允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音符号的规则。

A collection myColl has the following documents:myColl集合包含以下文档：

{ _id: 1, category: "café", status: "A" }
{ _id: 2, category: "cafe", status: "a" }
{ _id: 3, category: "cafE", status: "a" }

The following operation includes the collation option:以下操作包括排序规则选项：

db.myColl.findOneAndUpdate(
   { category: "cafe" },
   { $set: { status: "Updated" } },
   { collation: { locale: "fr", strength: 1 } }
);

The operation returns the following document:该操作将返回以下文档：

{ "_id" : 1, "category" : "café", "status" : "A" }

Array Update Operations with arrayFilters使用arrayFilters执行阵列更新操作

Note

arrayFilters is not available for updates that use an aggregation pipeline.不适用于使用聚合管道的更新。

New in version 3.6.版本3.6中的新功能。

Starting in MongoDB 3.6, when updating an array field, you can specify arrayFilters that determine which array elements to update.从MongoDB 3.6开始，在更新数组字段时，可以指定确定要更新哪些数组元素的arrayFilters。

Update Elements Match arrayFilters Criteria更新元素匹配arrayFilters条件

Note

arrayFilters is not available for updates that use an aggregation pipeline.不适用于使用聚合管道的更新。

Create a collection students with the following documents:创建一个包含以下文档的集合：

db.students.insert([
   { "_id" : 1, "grades" : [ 95, 92, 90 ] },
   { "_id" : 2, "grades" : [ 98, 100, 102 ] },
   { "_id" : 3, "grades" : [ 95, 110, 100 ] }
])

To modify all elements that are greater than or equal to 100 in the grades array, use the filtered positional operator $[<identifier>] with the arrayFilters option in the db.collection.findOneAndUpdate method:

db.students.findOneAndUpdate(
   { grades: { $gte: 100 } },
   { $set: { "grades.$[element]" : 100 } },
   { arrayFilters: [ { "element": { $gte: 100 } } ] }
)

The operation updates the grades field for a single document, and after the operation, the collection has the following documents:该操作将更新单个文档的grades字段，操作完成后，集合将包含以下文档：

{ "_id" : 1, "grades" : [ 95, 92, 90 ] }
{ "_id" : 2, "grades" : [ 98, 100, 100 ] }{ "_id" : 3, "grades" : [ 95, 110, 100 ] }

Update Specific Elements of an Array of Documents更新文档数组的特定元素

Note

arrayFilters is not available for updates that use an aggregation pipeline.不适用于使用聚合管道的更新。

Create a collection students2 with the following documents:使用以下文档创建students2集合：

db.students2.insert([
   {
      "_id" : 1,
      "grades" : [
         { "grade" : 80, "mean" : 75, "std" : 6 },
         { "grade" : 85, "mean" : 90, "std" : 4 },
         { "grade" : 85, "mean" : 85, "std" : 6 }
      ]
   },
   {
      "_id" : 2,
      "grades" : [
         { "grade" : 90, "mean" : 75, "std" : 6 },
         { "grade" : 87, "mean" : 90, "std" : 3 },
         { "grade" : 85, "mean" : 85, "std" : 4 }
      ]
   }
])

The following operation finds a document where the _id field equals 1 and uses the filtered positional operator $[<identifier>] with the arrayFilters to modify the mean for all elements in the grades array where the grade is greater than or equal to 85.

db.students2.findOneAndUpdate(
   { _id : 1 },
   { $set: { "grades.$[elem].mean" : 100 } },
   { arrayFilters: [ { "elem.grade": { $gte: 85 } } ] }
)

The operation updates the grades field for a single document, and after the operation, the collection has the following documents:该操作将更新单个文档的grades字段，操作完成后，集合将包含以下文档：

{
   "_id" : 1,
   "grades" : [
      { "grade" : 80, "mean" : 75, "std" : 6 },
{ "grade" : 85, "mean" : 100, "std" : 4 },{ "grade" : 85, "mean" : 100, "std" : 6 }    ]
}
{
   "_id" : 2,
   "grades" : [
      { "grade" : 90, "mean" : 75, "std" : 6 },
      { "grade" : 87, "mean" : 90, "std" : 3 },
      { "grade" : 85, "mean" : 85, "std" : 4 }
   ]
}

Use an Aggregation Pipeline for Updates使用聚合管道进行更新

Starting in MongoDB 4.2, db.collection.findOneAndUpdate() can accept an aggregation pipeline for the update. 从MongoDB 4.2开始，db.collection.findOneAndUpdate()可以接受更新的聚合管道。The pipeline can consist of the following stages:管道可包括以下阶段：

Using the aggregation pipeline allows for a more expressive update statement, such as expressing conditional updates based on current field values or updating one field using the value of another field(s).使用聚合管道可以实现更具表现力的update语句，例如基于当前字段值表达条件更新，或者使用另一个字段的值更新一个字段。

For example, create a collection students2 with the following documents:例如，使用以下文档创建students2集合：

db.students2.insert([
   {
      "_id" : 1,
      "grades" : [
         { "grade" : 80, "mean" : 75, "std" : 6 },
         { "grade" : 85, "mean" : 90, "std" : 4 },
         { "grade" : 85, "mean" : 85, "std" : 6 }
      ]
   },
   {
      "_id" : 2,
      "grades" : [
         { "grade" : 90, "mean" : 75, "std" : 6 },
         { "grade" : 87, "mean" : 90, "std" : 3 },
         { "grade" : 85, "mean" : 85, "std" : 4 }
      ]
   }
])

The following operation finds a document where the _id field equals 1 and uses an aggregation pipeline to calculate a new field total from the grades field:以下操作将查找_id字段等于1的文档，并使用聚合管道从grades字段计算新字段total：

db.students2.findOneAndUpdate(
   { _id : 1 },
   [ { $set: { "total" : { $sum: "$grades.grade" } } } ],  // The $set stage is an alias for ``$addFields`` stage
   { returnNewDocument: true }
)

Note

The $set used in the pipeline refers to the aggregation stage $set and not the update operator $set.管道中使用的$set指的是聚合阶段$set，而不是更新运算符$set。

The operation returns the updated document :该操作将返回更新后的文档：

{
  "_id" : 1,
  "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 90, "std" : 4 }, { "grade" : 85, "mean" :85, "std" : 6 } ],
  "total" : 250
}